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Neo MV1C completely dead

Mitsurugi-w

Mitsurugi-w

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I bought this and it's completely dead. I get nothing on screen not even the grid screen when no cart is inserted. No obvious physical damage. Reflowed a few chips just for the hell of it with no change. It looks like a simply design so maybe some of the Neo guys here have an idea.
 
you verify voltage to any of the ICs? Basically asking if you verified the fuse wasn't popped ;)
 
Yeah fuse was fine. Tested with a meter. Removed it and cleaned it as well as the fuse holder during initial testing.
 
Sounds like it has some bad SRAM chips, that is usually the cause of the black/no screen issue. Also doesnt hurt to give the cart slot connector a good cleaning.
 
I should still get a cross hatch without a cart right?
 
Mitsurugi-w said:
I should still get a cross hatch without a cart right?
Click to expand...
yup, no cart gets you those cross hatch. If you insert a cart and you only get a black screen, check the dip switches. My top loader didn't wanna play anything until i put all the dip switches to the same position.
 
Dips are fine. No image no matter what. With or without cart.
 
I 2nd the bad ram idea. I would also check the bios.
 
I can surely say what "might not" be the cause;

- Even if you have a dead CPU or dead BIOS you should see garbage on screen and "click-of-death"


One other "simple" thing to check is the dip switch 8. If it is accidentally ON or somehow stuck internally at ON position the system just pauses hence nothing on screen.

By the way, do you have at least a black video or nothing?

Another thing to check is to make ALL the dip switches ON and see if you see the RAM tests running.

I would recommend to test it with neogeo diagnostics BIOS but since its a 1C then its a pain in the neck to desolder the BIOS, solder lots of wires to an IC socket which you can fit a 27C1024...

Good luck...
 
I get nothing. The TV flashed for a second when the super gun is powered on but resumes the No Signal screen immediately.

I still get nothing with all 8 dips in the ON position. I ordered a NeoBiosMasta to install a week ago but it hasn't arrived yet.
 
I bought an installed a NeoBiosMasta with Neo Diagnotic bios and I still get nothing but a black screen on this one.
 
if you remove the BIOS from the socket of the Biosmasta and power in the board, do you get anything? Like any clicking and screen flashing? The 68k might be dead. But I'm no expert.
 
There is slight screen flashing with a bios installed. But its very subtle.
 
That would be the watchdog resetting the board would be my guess. Any damage to the board from a battery leaking?

If not - have you got a logic probe? I'd be starting from square 1 and working out from there, - check for clock signal and reset signal on the 68k to see if it's doing anything at all. Could be a bad crystal (you can probe it to see if it's doing it's job), bad 68k, if there's clock signal and reset then as others have suggested the RAM would be the next thing to check. Any trace damage?
 
If there is no video, no click-click sound, no garbage screen my guess is the GPU (big custom) is toast.

Based on my experiences with the MVS PCBs that you "should" see a garbage screen (you should see it not subtle but all the time) with full of colorful characters even if your BIOS is fried (even missing) OR the 68000 is fried. You may not always hear the click-click sound (the watchdog resetting the PCB) because the audio amplifier may also have been toast.

Checking the data/adres lines with probe should reveal if your PCB is running blind. Worst case scenario is that your PCB is running blind as well as the audio amp is toast (once I fixed such a PCB, was a bitch to diagnose).

Disabling the watchdog (there should be a solder point which the silk screen says WD - just put a solder blob there) helps in diagnosing further problems. It'll let the PCB continue booting (if the CPU & BIOS is OK) to reveal further error messages or evidence of other problems.
 
I tried a few things I was told to try. I replaced the crystal and the WRAM because I was told it could cause a boot failure. No change. I tried jumping the WD circuit and no change.

So sounds like the custom is toast?
 
Could be if there's no trace damage, did you probe the 68k to see if it's talking?
 
With a logic probe or an O-scope?
 
Logic probe will tell you enough to know if you're getting a clock signal and if the reset line is doing what it should be and allowing the board to boot

The O-scope comes in when you need to see more information than the logic probe can give you
 
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